1. Field of the Invention
This invention relates to an actuator-cylinder valve connection, and more particularly, to a connection mechanism therebetween that protects the cylinder valve stem sealing mechanism from forces imposed on the actuator and transmitted through the valve into the cylinder.
2. Background Information
In the past, high pressure compressed gas cylinder valves were operated almost exclusively by manual means; such as handwheels, levers, and wrenches. Recently, however, the use of automatic actuators have become more and more popular, especially in the semiconductor industry.
Automatic actuators, which may be pneumatic, electrical, or hydraulic, usually result in a significantly larger volume and mass when compared to the manual type actuator which is operated by a handwheel or lever connected to an outer valve stem threaded into a nut, which, in turn, is threaded onto the valve body. Consequently, this larger volume and mass of the automatic actuators constitute a larger weight atop the valve. This added weight is of particular importance should the cylinder, the valve, or the actuator itself be subjected to an impact force. Such forces may originate from a projectile or some other form of inadvertently applied impact force. These impact forces may also be generated simply by the cylinder falling over.
Thus, shock forces imposed in either manner may result in large direct impact and/or inertial forces being transmitted through the actuator to the valve connection, and eventually into the cylinder.
These manual and automatic valve actuator-cylinder valve connections commonly transmit direct impact forces imposed on the actuator, or inertial forces generated by the actuator, into a mechanical sealing mechanism between the actuator and cylinder valve which prevents the cylinder compressed gases from entering into the actuator or escaping to the environment.
U.S. Pat. Nos. 4,706,929 and 4,776,562 relate to automatic actuators. Typically, in an automatic actuator, as disclosed in the above patents, the sealing mechanism is formed by a diaphragm set seated against a shoulder of the valve body and held in place by a downward extension of the cylindrical housing of the automatic actuator. This extension abuts against the diaphragm set and has threads which engage those in the valve body. The forces discussed hereinabove tend to loosen the threaded connection between the extension of the housing and the valve body.
The sealing mechanism for a manually actuated actuator is similar to that for the automatic actuator, the main difference being that a bonnet nut and handwheel replace the automatic actuator with its cylindrical housing. Any axial or lateral forces applied to the handwheel of the manually actuated actuator pass into the outer valve stem into the bonnet nut, resulting in a disturbance or damage to the sealing mechanism formed between the bonnet nut and the valve body, and/or a loosening of the torque of the bonnet nut.
One feature of the present invention is to provide an actuator-cylinder valve connection that isolates the mechanical sealing mechanism from any such direct impact and/or inertial forces. In the present invention, these forces are circumvented around the sealing mechanism so as not to adversely affect the integrity of the seal.
Accordingly, it is a primary object of the present invention to provide an actuator-cylinder valve connection that will isolate the valve stem sealing mechanism located at the interface between the actuator and the valve from inertial forces generated by the actuator and/or impact forces applied to the actuator.
It is another object of the present invention to provide an actuator-cylinder valve connection whose integrity will be independent of cylinder pressure.
It is another object of the present invention to provide a connection mechanism which is readily adaptable to present-day manual and automatic actuator designs.
It is a broad object of the present invention to provide such a connection that is durable and reliable, and which can be easily and economically manufactured and assembled.